Emissions traps are used to trap and thus remove emissions from exhaust gas to reduce discharge of emissions to the atmosphere. From time to time, emissions traps are “regenerated.” During such regeneration events, emissions trapped by an emissions trap are purged therefrom for further use of the emissions trap.
A particulate filter is one type of emissions trap. A particulate filter is used to trap and thus remove soot from exhaust gas. It is regenerated by burning off the particulate filter thereby.
A NOx trap is another type of emissions trap. A NOx trap is used to trap and thus remove NOx (i.e., oxides of nitrogen) from exhaust gas when the exhaust gas is relatively lean (i.e., has excess oxygen). The NOx trap is regenerated in the presence of a NOx-reducing agent [e.g., fuel, hydrogen (H2), carbon monoxide].